# The Suitability of Dried Blood Spot Sampling for Pharmacokinetic Studies in Veterinary Medicine

## TL;DR

This study explores the use of dried blood spot sampling as a minimally invasive method for measuring drug levels in cats and horses during surgery, showing promise for veterinary pharmacology.

## Contribution

The study introduces a standardized DBS protocol and validates LC-MS/MS methods for quantifying anesthetic agents in veterinary species.

## Key findings

- DBS sampling showed satisfactory agreement for medetomidine in cats, meeting EMA guidelines with 75.6% of measurements within ±20%.
- Ketamine and lidocaine results indicated potential but require further optimization and investigation.
- DBS is identified as a promising minimally invasive alternative for veterinary pharmacokinetic studies.

## Abstract

Dried blood spot (DBS) sampling is a microsampling technique that involves collecting small volumes of blood on absorbent paper for later analysis. It offers several advantages, including minimal invasiveness, reduced blood volume requirements, and enhanced analyte stability. While widely used in human medicine for neonatal screening, diagnostics, pharmacokinetics, forensics, and infectious disease surveillance, its application in veterinary medicine remains limited. However, DBS sampling holds great potential in veterinary pharmacokinetic research by minimizing animal discomfort and simplifying sample handling. This study investigated the feasibility of using DBS sampling to quantify ketamine, medetomidine, and lidocaine levels in cats and horses undergoing surgery. The primary objectives were to develop a standardized DBS collection protocol, optimize LC-MS/MS analytical methods, and compare DBS with plasma samples.

Dried blood spot (DBS) sampling has emerged as a promising microsampling technique in biomedical and clinical research, offering advantages such as reduced invasiveness, minimal blood volume requirements, and enhanced analyte stability. Although well established in human medicine for neonatal screening and diagnostic applications, its potential in veterinary pharmacology remains underexplored. This study investigated the feasibility of using DBS samples to quantify anesthetic agents—ketamine and medetomidine in cats and lidocaine in horses—during routine surgical procedures at a veterinary teaching hospital. A standardized DBS collection protocol was developed, and LC-MS/MS methods were validated for the quantification of target analytes in both DBS and plasma samples. These methods were subsequently applied to real samples collected during anesthesia to conduct pharmacokinetic analyses. Comparative evaluations, including Bland–Altman analysis, assessed the suitability of DBS samples for pharmacokinetic studies in veterinary medicine. Preliminary results indicated satisfactory agreement for medetomidine, meeting EMA guidelines, with 75.6% of mean values falling within ±20% of paired measurements. Results for ketamine (46.9%) were promising but require further optimization, while those for lidocaine (21.4%) highlighted the need for additional investigation. These findings underscore the potential of DBS sampling as a minimally invasive alternative for pharmacokinetic studies in veterinary medicine, particularly for medetomidine, while identifying areas for further methodological refinement. Future research should optimize DBS techniques and expand their application to other drugs and species, broadening their impact on veterinary pharmacology.